New Scientist has a feature near the end of the magazine where reader questions shared in one issue are answered by other readers who send in submissions that are selected to appear in a later issue.
Below is a question and six answers related to when a theory becomes a fact. The answers make a lot of sense.
Even though I've been aware that when something is called a theory, this doesn't mean that it isn't a well-proven means of describing reality. But this is how many people view a theory -- as something speculative, as when we say "I've got a theory about why my car won't start."
All the answers are great, which isn't surprising, since they're chosen by staff of New Scientist, who obviously know a lot about science. I particularly like #3, which encapsulates some key features of science in just a few sentences.
Theories are interpretive structures that link facts. The more facts, the better. If facts are discovered that don't fit the theory, scientists embark on a search for a better theory. So science makes progress by being flexible, not viewing any truth as set in stone, since it can always be dislodged by fresh facts that call into question the validity of a theory.
Religions can't compete in this Game of Truth, because they typically are founded on faith, not facts. Even religions which claim to be a science of sorts aren't really open to having their Theory of God, or whatever, subjected to modification, improvement, or even rejection.
When does a theory become a fact and who decides?
Answer 1: A theory never becomes a fact. It is an explanation of one or more facts.
Answer 2: A well-supported evidence-based theory becomes acceptable until disproved. It never evolves to a fact, and that's a fact.
Answer 3: Many scientists, including the late Stephen Hawking, are happy to say that a theory never becomes a fact. It is always an interpretive structure that links facts, which are themselves reproducible experimental observations.
The "truth" of a theory is determined by its usefulness in linking the largest number of facts and predicting new ones that haven't been observed yet. Discovery of facts that don't fit the theory will lead to the search for a new theory.
Answer 4: This question misunderstands what a theory is in the same way that creationists dismiss evolution as "just a theory."
A theory isn't speculation about what might be true. It is a set of propositions that seek to explain a particular phenomenon or set of facts. A theory can be tested and shown to be accurate or modified as the evidence requires. Even when a theory is accepted as fact, it remains a theory.
Answer 5: While a scientific theory such as Issac Newton's theory of gravitation makes an infinite number of predictions, it can only be verified by a finite number of observations, so it can never be seen as irrefutably correct. In philosophy, this is the problem of induction.
The fact that science rests on rather shaky epistemological foundations opens it to attack from anti-science movements, for example when creationists claim that Darwinian evolution is "only a theory." All science is, to some extent, "only theory," but its great strength is that theories that don't fit real world observations are eventually discarded. This has happened with Newton's theory of gravitation, now seen to be a special case of general relativity.
So in reality, in science we do not have facts or proof, all we have is the best available, most widely accepted theory at the time.
Answer 6: Evolutionary pressures have favoured some organisms that are aware of their surroundings and able to react to them. Humans have become rather good at this.
We also have curiosity, which leads us to look hard at our surroundings and try to make sense of what we find. So, we gather information, and try to invent theories that could explain what we see. The better theories don't just explain all the data so far observed, they enable predictions. If confirmed by data, this strengthens our reliance on the theory.
Take satnav systems, for example. These rely on the predictions of relativity and quantum theories. Every time a satnav system is used, the theories it was based on are tested again. But, until we know "everything," theories, even the successful ones, will still be theories.